UNITED NATIONS  Secretary-General Ban Ki-moon urged the international community Tuesday to build the foundations for peace in Somalia by strengthening U.N. political efforts and deploying a new 8,000-strong multinational force.

This could pave the way for the withdrawal of Ethiopian troops who helped Somalia rout an Islamic movement in December 2006 and the possible deployment of a U.N. peacekeeping force of up to 27,000 soldiers and 1,500 police, he said.

In a long-delayed report to the Security Council, Ban said the United Nations is developing a three-pronged strategy to promote dialogue between Somalia's transitional government and opposition elements.

The goal, he said, is to ensure "a credible security presence" even before a formal cease-fire, and to strengthen government institutions, humanitarian aid and economic recovery.

Somalia has not had a functioning government since clan-based warlords toppled dictator Mohamed Siad Barre in 1991 and then turned on each other, sinking the poverty-stricken nation of 7 million people into chaos.

Its weak transitional government, backed by Ethiopian troops, is struggling to quash a re-emerging Islamic insurgency that has killed thousands of civilians. The insurgents, whom U.S. officials have linked to al-Qaida, are backed by Ethiopia's archenemy Eritrea.

In December, the Security Council called on Ban to plan for the possible deployment of U.N. peacekeepers to replace the African Union force now in Somalia. The council was reiterating a request it initially made in August that Ban rejected.

The council is scheduled to discuss Somalia on Thursday.

A fact-finding mission led by the U.N. Department of Peacekeeping Operations developed four scenarios -- which could take place sequentially -- leading to the deployment of a possible U.N. peacekeeping operation.

The first represents the current situation where the transitional government is trying to engage the opposition in political dialogue and the African Union force in Somalia remains at its current level of 2,600 troops, he said.

Under this scenario, Ban said, the U.N. would seek to move a substantial number of staff from Nairobi to Somalia.

The second scenario requires 60 to 70 percent of the opposition to support a political dialogue and an improvement in security so the U.N. can have a stronger presence in Mogadishu, Ban said. Under this scenario, he said, the U.N. would relocate to the capital, which would require beefed-up security arrangements.

The third scenario envisions 60 to 70 percent of the opposition implementing a code of conduct on the use of arms, and agreement on a gradual withdrawal of Ethiopian forces, Ban said.

Under this scenario, a broad-based political agreement would be followed by deployment of "an impartial stabilization force ... to allow the withdrawal of Ethiopian forces, prevent a security vacuum and provide impetus to the political dialogue," he said.

An estimated 8,000 troops, well-trained in counterinsurgency and counter-terrorist techniques, would be required, together with international police officers, Ban said.

"A United Nations force could not be tasked with this role," he stressed, citing the U.N. military operation in Somalia in 1993 that undermined U.N. political and humanitarian efforts.

"As a result, the Security Council could consider this option only if offers were forthcoming from capable member states ready to form a coalition of the willing," Ban said.

In the fourth scenario, 70 percent of the parties must agree to share power, renounce violence, lay down arms, and support deployment of a U.N. peacekeeping mission, with 15 to 21 infantry battalions and up to 27,000 troops and 1,500 police, he said.

(This version CORRECTS that the Islamic movement was routed in December 2006, not January 2007.)

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